New fuzzing model providers:

[Markoutte]

Description

• collection model provider creates some empty collections of set, list, map, etc.
• array model provider creates empty and not-empty arrays
• char to string model which combines constants into string
• enum model providers creates values of enums
• added extra primitive model providers: default values and values of wrappers
• object model provider now can generate objects with another types as a parameter

Bug fixes and workarounds:

• UtAssembleModel fails to generate test with java.lang.String()
• Several NPEs because of generating null values for unknown types
• NullModelProvider generates models for the primitive parameter

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

Automated Testing

• org.utbot.framework.plugin.api.ModelProviderTest
• org.utbot.examples.manual.PredefinedGeneratorParameters.testFuzzingSimple

Checklist:

• The change followed the style guidelines of the UTBot project
• Self-review of the code is passed
• The change contains enough commentaries, particularly in hard-to-understand areas
• New documentation is provided or existed one is altered
• No new warnings
• Tests that prove my change is effective
• All tests pass locally with my changes